The proposed study is designed to establish that the endothelin receptor antagonist L-753,037 lowers blood pressure in African-American patients with essential hypertension, while simultaneously maintaining an acceptable safety and tolerability profile. African Americans appear to have higher levels of endothelin than Caucasians. Targeting the hypertensive African-American patient population, in whom endothelin receptor blockade is postulated to be an effective means of blood pressure reduction, would help to demonstrate the utility of this drug in the treatment of hypertension. Amlodipine at 5 mg per day has been chosen as an active comparator because it is effective in the treatment of essential hypertension in African Americans. Furthermore, the adverse event profile of amlodipine (vasodilatory in nature) is similiar to what is expected to be found when patients are administered an endothelin receptor antagonist.